The present invention relates to moving racks that support relatively heavy materials and, in particular, to crank mechanisms for moving such racks.
Relatively long, heavy, substantially flat objects, such as angle iron or other elongate structural shapes and sheet steel, are common in industrial applications. For example, these objects or materials are often used in manufacturing operations as component parts in a final product or facility. Since product manufacturing is typically a continual operation, it is often necessary to carry an inventory of these materials. In order to make efficient use of available floor space, such long, relatively flat objects are best stored horizontally in vertically stacked racks.
Current vertical storage racks for elongated materials are generally of three types: xe2x80x9cpigeon holexe2x80x9d-type racks; racks with manual rollout drawers; and racks with automated rollout drawers. The xe2x80x9cpigeon holexe2x80x9d rack typically requires one or more persons to push or pull individual pieces in or out of a storage rack. The obvious drawback of the xe2x80x9cpigeon holexe2x80x9d rack is the size limitation of material that can be stored in the rack. Large heavy materials cannot be easily manipulated by one or two persons.
The rack with manual rollout drawers improves upon the xe2x80x9cpigeon holexe2x80x9d rack in that the moveable drawers allow access to the relatively long, materials by a fork lift or a sling on a hoist. However, this rack may also be ergonomically hazardous to an individual opening or closing a drawer. The inherent weight of the materials coupled with friction of the slidable surface may require large amounts of force to open and close the drawers. The individual indexing the drawers may, for example, strain his or her back when pulling the drawer open or pushing it closed. This is especially true for racks at a level other than between the individual""s waist and shoulders. Additionally, lower racks may require the individual to crouch to reach the drawer, thus compounding the ergonomic hazards. Similarly, drawers above shoulder level may require the individual to stand on a ladder or stool. The use of a ladder or a stool increases the risk of injury due to falling.
Racks with automated rollout drawers have been developed to reduce the risk of injury to individuals opening and closing the racks. Unfortunately, many of the automated racks require the use of complex mechanical and electrical equipment, including motors, chains and sprockets, and rack and pinion systems. The complexity of these automated systems increases the necessary maintenance costs associated with the racks. In the event of required maintenance, such as a broken chain, production may be interrupted causing costly delays because access to materials required for production is impossible.
Based on the foregoing, there is a need for racks that support relatively long, heavy materials to have rollout drawers which do not require an individual to place himself or herself in an ergonomically compromising position. It would also be advantageous for such racks to have a simple design such that construction and maintenance costs allow for an affordable product and that the risk of downtime is reduced.
The present invention provides a rack with rollout drawers and a crank mechanism for moving the drawers that is particularly well suited to an individual worker opening and closing the drawers. The crank mechanism is relatively simple such that construction and maintenance of the rack are minimal.
The rack with rollout drawers of the present invention includes a rack assembly including a plurality of drawers arranged vertically, side frames and a drawer drive assembly. Each drawer may be independently moved in and out relative to the side frames by riding on wheels along a portion of the side frames. Two wheels of each individual drawer are connected to each other by a main shaft such that one of the wheels travels along a portion of one side frame, and the other wheel travels along a portion of the other side frame.
The individual drawers may also have a coupling device or crank shaft mechanism that is connected to the main shaft of the drawer. The coupling device can impart movement to the main shaft. The coupling device may include at least one coupling shaft and a shaft moving unit. In one embodiment, the shaft moving unit may include a crank handle connected to the coupling shaft. The coupling shaft may be in substantially the same plane as the main shaft and perpendicular to the main shaft.
The drawer drive assembly may also include a gear mechanism connected to the main shaft. The gear mechanism may have a first gear attached to the main shaft. The drawer drive assembly may also have a second gear attached to the coupling shaft and engaging with the first gear attached to the main shaft. The gear mechanism provides a substantial mechanical advantage for a person attempting to open or close a drawer. Thus, the physical exertion required of the person is decreased and, with it, the possibility of physical injury.
The wheels of the individual drawers may be attached to the main shaft at a side wall of the drawer. The drawer may also include a flange bearing adjacent to each wheel attached to the main wheel. Additionally, the flange bearing may be spaced from the wheel.
The side frames of the rack can include track members, with an inner surface and an outer surface, for the drawer wheels to travel along. The wheels may then travel along the track member by riding between the inner surface and outer surface of the track member. The flange bearing, if provided, may be located at least partially inward of the inner surface.
The support rack of the present invention may also include a housing member to surround at least a portion of the gear mechanism. The housing member may provide additional support to the main shaft and may also protect the gear mechanism from damage for objects being placed or stored upon the drawer.
Based on the foregoing summary, a number of worthwhile aspects of the present invention can be readily identified. The storage rack allows a single person to open and close the rack with reduced effort and risk of injury. The gear mechanism provides a mechanical advantage to the individual operating the rack to enhance operation. Additionally, the drawer drive assembly is a simple combination of gears, drive shafts and wheels. Thus, the simple design provides an affordable rack with minimal on-going maintenance costs. The design of the present invention also lends itself to automation by the mere connection of a motor to the coupling shaft. This minor increase in complexity can further facilitate drawer movement.
Additional advantages of the present invention will become readily apparent from the following discussion, particularly when taken together with the accompanying drawings.